Motor-controller.



W. C. STEVENS.

MOTOR CONTROLLER.

APFLlCATlON FILED NOV. 30, $914.

11,277,499, Patented Sept. 3, 1918.

ina'rrun STATES PATENT" mm.

wnmrurc. STEVENS, 0! sum,

xerox-commune.

To all whom it may concern:

a Be it known that I, WILLIAM C. S'rnvsNs,

, s ams 0! Letters ram-u.

- Application fled'llovembcr 30, 1914. Serial 10.87438},

a citizen of the United States, residing at 7 Summit, in the county of Union and State of New Jersey, haveinvented new and use ful Improvements in Motor-Controllers, of

which the following is a full, clear, concisca and exact description, reference being ha, to the accompanying drawing, forming a part of this specification.

This invention relates to improvements in motor controllers and more particularly to controllers for decelerating electric motors operating under varying loads.

- The invention has among its objects .to

"provide simple and eflicient decelerating means tending to automatically compensate for load variations and also acting to limit the rate of deceleration to insure a adual slow-down irrespective of load con 'tions. A further object is to provide simple and efiicient means to limit the rate of deceleration by. varying the range of efiectivenws of the decelerating means in synchronism with the movement of the driven mechanism within the slow-down period.

Various other objects and advantages 01" the invention will hereinafter appear.

The invention will now be more specifically described in connection with the accompanying drawing, which diagrammatis cally illustrates one embodiment thereof. However, it should be understood that the invention may be embodied in other forms falling within the scope of the appended claims.

As illustrated, the controller is employed to regulate a compound motor 1' having an armature A, a series field winding F and a shunt field winding 'F'. For starting and accelerating the motor 1 them is provided a main line switch 2 and a series resistance R controllable by switches 3. It is, of

' course, to be understood that the switches 2 and 3 may be of any preferred type and controlled in any preferred manninand that the resistance B may be used for deoeleration as well as acceleration. However, an additional decelerating resistance B is provided to be automatically hereinafter set forth. i

The resistance R is, designed to be connected in shunt with the motor armature and, to this end is provided with a suitable control switch 4' which", it maybe assumed,

is closed automatically .at the desired time,

controlled, as

-. movement '0 Patented Sept. 3, 1918.;

as for example, immediately following reinsertion of the series resistance R.

the shunt resistance R is variable and provided with a suitable controlling element 5' illustrated as of the cross-head type and operable by a pilotmotor 6 having an armature a and a'shunt field winding f. The motor 6 is reversibleto move the resistance controlling element 5 in opposite directions to decrease or increase resistance R and is controlled by magnetic reversing switches 7 and 8 which are automatically controlled by a tachometer T, a suitable switch 9 being provided to render said magnetic switches mert when not required for use.

t The tachometer T, which may be of any preferred form, is schematically illustrated as provided with a dial lO and a needleaor pointer 11 adapted to 006 to with contacts 12 and 13 on the dial to selectively control the switches 7 and 8. The tachometer mechanism is operatively connected by suitable means 14 to the driven mechanism,

ewise opera- I tively connected to the driven mechanism.

lected for illustration comprising a link coni necting 16 movable with the driven mechanism. With this, arrangement the dial will be rotated in opposi directions at the comthe dial with a double-acting cam menoement and completionof one revolution, of the gear 15 and ,thus it will be asumetb that the range of movement of the gear 15 to restore the dial to normal podtion constitutes the range which the. gear is to be slowed downto the desired speed by the armature shunt resistance R. The movement of the dial during deceleration corresponds in direction to that of the tachometer needle when indicating diminution.

Thus it will be M that with the armature shunt 00 included in circuit the motor will be caused to slow down and' under difierent load the tachometer needle'will-be deflected into ont'with 1 1 m ing to the character of load variations, to

increase and decrease the shunt resistance.

This compensates for load variations while.

the movement of the dial insures a gradual 5 deceleration irrespective of load conditions.

As above stated, the dial is moved in the same direction as the needle when indicating" deceleration, thereby causing one of its con- 'tacts to follow and the other to recede from said needle and in synchronism with the driven mechanisms. In consequence, if, when the armature shunt is completed the slow-down is gradual and the rate thereof does not exceed the rate of movement of the dial, then the relation between the contacts and the needle will not be disturbed. On the other hand, if the slow-down is abrupt then the needle will move faster than the dial, thereby tending to overtake the receding contact and thereafter if the rate of deceleration drops oil the dial will tend toovertake the needle. This in turn will result in varying the shunt resistance in accordance .with the speed of the motor and furthermore in accordance with the position of the dial whereby the net result will be a varying limit to the degree of deceleration according to the position of the driven mechanism and in consequence gradual de- 1 celeration irrespective of load conditions. It will, of course, be understood that the contacts on the dial may be adjusted according to the results desired;

In the controller illustrated it may be assumed that the needle moves clockwise as the speed of the driven mechanism increases and that the dial moves in a corresponding direction to the dotted line position upon initial movement of the driven mechanism. Then the contact 13 would be employed to direct operation of the pilot motor to exelude the armature shunt resistance for inareasing the slowdown efiect on the motor While the contact 12 would be employed for the opposite purpose Under such conditions the needle would engage the contact 13 upon initial closure'of the armature shunt circuit and then advance to engagement with contact 12 to decrease the slow down eifect of resistance R should the rate of slow down become excessive.

Although the circuit connections are very simple, the. same will now be briefly described. The circuit of the motor 1 may be traced from line L through switch 2 when closed, by conductor through the armature A, and thence through the series field winding and resistance R to line L, while a branch extends from conductor 20 by conductor 21 thro h the shunt field winding 35" to line L. en switch 4 is closed then a circuit is completed from the left hand terminal of the motor by conductor 22 through resistance R and thence through as said switch 4: to the right of the armature. Considering now the pilot motor, the field is connected by conductor 23 directly to line L and by. conductor 24 to line L, whereas its armature circuit varies according to the operation of the switches. 7 and 8. With switch 7 energized circuit extends from line L by conductors 25 and 26 through the down contacts 8" of switch 8, by conductor 27 through the armature a from right to left, by conductor 28 through the up contacts 7 of switch 7 by conductors 29 and 30 through switch 9 when closed to conductor 24 and thence to line L. On the other hand, with switch 8 energized circuit is closed from line L by conductors 25 and 26 through the down contacts 7 of switch 7 through the armature a from left to right and t ence through the up contacts 8 of switch 8 to lineL'. The energizing circuit of switch 7 extends from line L byconductor 25 through the tachometer needle 11' and contact 13 by conductor 31 through the winding of said switch to conductor 29 and thence to line L as already traced, while the energizing circuit of switch 8 extends through the tachometer needle and contact 12 by conductor 32 through the winding of switch 8 to conductor 29.

While for simplicity of illustration the controller has been applied to a non-reversible motor, it will be readily apparent that the same is also applicable to a reversible motor. Further, it will be apparent that the controller is applicable to alternating as well as direct current motors.

What I claim as new and desire to secure by Letters Patent is; a

1. In a controller for a motor operating under varying load conditions, in combination, power operated decelerating means and control means therefor includin co6perating devices, one of said devices ing operab e in response to motor speed variations for control of said decelerating means to compensate for load variations and the other of said devices being normally stationary and being adjustable tocontrol the rate of deceleration.

2. In combination, a motor operating under varying load conditions, power oper- 115 ated decelerating means for said motor, control means for said decelerating means including cooperating devices, one of said devices being operable in response to speed variations of said motor and the other of 120 said devices being normally stationary and means subjecting the latter device to adjustment by said motor whereby said devices cotions in the speed of said motor, said first mentioned member having means associated therewith to limit the movement thereof to a predetermined part of the range of operation of said motor.'

4. In combination, a motor, a shunt resist ance and a series resistance for the circuit thereof, means for varying the resistance of said shunt to decelerate said motor, cooperating controlling members therefor to vary the effect thereof, one of said members being movable in response to variations in the speed of said motor to compensate for the effect of load variations, and means for subjecting the other of said members to movement by said motor to establish a maximum rate of deceleration irrespective of load conditions.

5. In combination, a motor, speed r ulating means therefor, relatively movab e cooperating members controlling said means to vary the effect thereof, one of said members comprising a speed indicator for the motor and means including a part driven by the motor for establishing and interrupting a drive between the other of said controlling members and the motor according to the position of said part, said drive when estab lished insuring operation of said member in synchronism with the motor.

In witness whereof, I have hereunto subscribed my name in the presence oftwo witnesses.

WILLIAM C. STEVENS. Witnesses:

T. D. MONTGOMERY, LAURA E. SMITH. 

